Leukemia inhibitory factor shortens primary cilia by upregulating C-C motif chemokine 2 in human neural stem/progenitor cells.

Primary cilia on neural stem/progenitor cells (NSPCs) play an important role in determining cell fate, although the regulatory mechanisms involved in the ciliogenesis remain largely unknown. In this study, we analyzed the effect of the leukemia inhibitory factor (LIF) for the primary cilia in immortalized human NSPCs. LIF withdrawal elongated the primary cilia length, whereas the addition of LIF shortened it. Microarray gene expression analysis revealed that differentially expressed genes (DEGs) associated with LIF treatment were related with the multiple cytokine signaling pathways. Among the DEGs, C-C motif chemokine 2 (CCL2) had the highest ranking and its increase in the protein concentration in the NSPCs-conditioned medium after the LIF treatment was confirmed by ELISA. Interestingly, we found that CCL2 was a negative regulator of cilium length, and LIF-induced shortening of primary cilia was antagonized by CCL2-specific antibody, suggesting that LIF could influence cilia length via upregulating CCL2. The shortening effect of LIF and CCL2 on primary cilia was also observed in SH-SY5Y cells. The results of the study suggested that the LIF-CCL2 axis may well be a regulator of NSPCs and its primary cilia length, which could affect multiple cellular processes, including NSPC proliferation and differentiation.

Somatic mosaicism of the PI3K-AKT-MTOR pathway is associated with hemimegalencephaly in fetal brains.

It is known that somatic activation of PI3K-AKT-MTOR signaling causes malformations of cortical development varying from hemimegalencephaly to focal cortical dysplasia. However, there have been few reports of fetal cases. Here we report two fetal cases of hemimegalencephaly, one associated with mosaic mutations in PIK3CA and another in AKT1. Both brains showed polymicrogyria, multiple subarachnoidal, subcortical, and subventricular heterotopia resulting from abnormal proliferation of neural stem/progenitor cells, cell differentiation, and migration of neuroblasts. Scattered cell nests immunoreactive for phosphorylated-S6 ribosomal protein (P-RPS6) (Ser240/244) were observed in the polymicrogyria-like cortical plate, intermediate zone, and arachnoid space, suggesting that the PI3K-AKT-MTOR pathway was actually activated in these cells. Pathological analyses could shed light on the mechanisms involved in disrupted brain development in the somatic mosaicism of the PI3K-AKT-MTOR pathway.

A targeted educational programme improves fundamental knowledge of menstrual pain and endometriosis in young women: The Endometriosis Awareness Promotion Project.

RESEARCH QUESTION: Would a properly designed educational programme offered to young women improve their awareness and fundamental knowledge of menstrual pain and endometriosis? DESIGN: A multinational cross-sectional study using a pen-and-paper questionnaire among women aged 19-24 years was conducted between 2017 and 2019 to assess fundamental knowledge of menstrual pain and endometriosis. Improvement in knowledge was also analysed using a separate questionnaire completed before, and 1-3 months after, a group discussion, lecture on menstrual pain and endometriosis, or both. RESULTS: Among three groups of students (college [n = 271], medical [n = 877] and nursing [n = 763]), knowledge of menstrual pain and endometriosis was lowest among college students, modest among nursing students and fair among medical students (P < 0.001 for each). The experience of cyclical pain, even when painkillers were taken, was reported by 15.5%, 4.6% and 3.8% of students, respectively. Most students managed their cyclical pain by enduring it or by taking over-the-counter medication. An informative education programme with group discussions, lectures, or both, was successful in improving knowledge and consequences of menstrual pain and endometriosis. Proper education and dissemination of knowledge to college students failed to motivate them to visit gynaecologists; however, medical and nursing students became highly interested in visiting gynaecologists. CONCLUSIONS: An educational programme can improve awareness and knowledge of endometriosis and dysmenorrhoea among young women. The programme motivated nursing and medical students, but not college students, to seek medical attention for early detection and management of endometriosis.

High-grade transformation/dedifferentiation of an adenoid cystic carcinoma of the minor salivary gland to myoepithelial carcinoma.

High-grade transformation (HGT)/dedifferentiation is an unusual phenomenon in salivary gland carcinomas. Here we report a case of adenoid cystic carcinoma (ACC) with HGT/dedifferentiation to myoepithelial carcinoma, occurring in the epipharynx of a 42-year-old woman. The surgically resected tumor was a pedunculated mass, 31 × 25 mm in size, which had two histologically distinct carcinomatous areas, including a high-grade sarcomatoid area composed of pleomorphic spindle cells and an area consisting of low-grade typical ACC. These two components gradually changed from the low-grade to the high-grade component. MIB-1 index in the low-grade and high-grade component was 15% and 50%, respectively. An immunohistochemical profile of the high-grade component showed immunoreactivity for α-SMA, p63, calponin and focal S100, as well as for several cytokeratin markers, which were compatible with the features of myoepithelial carcinoma. In contrast, the immunohistochemical profile of the low-grade component coincided with that of typical ACC. This HGT/dedifferentiation to myoepithelial carcinoma is extremely rare. The pathogenesis of HGT/dedifferentiation in salivary gland carcinomas still remains largely unknown, regardless of the presence or absence of myoepithelial differentiation. Further studies are required due to the more aggressive biological behavior and poorer prognosis associated with ACC with HGT/dedifferentiation, compared with conventional ACC.

Bacterial contamination hypothesis: a new concept in endometriosis.

BACKGROUND: Endometriosis is a multifactorial disease that mainly affects women of reproductive age. The exact pathogenesis of this disease is still debatable. The role of bacterial endotoxin (lipopolysaccharide, LPS) and Toll-like receptor 4 (TLR4) in endometriosis were investigated and the possible source of endotoxin in the pelvic environment was examined. METHODS: The limulus amoebocyte lysate test was used to measure the endotoxin levels in the menstrual fluid and peritoneal fluid and their potential role in the growth of endometriosis was investigated. Menstrual blood and endometrial samples were cultured for the presence of microbes. The effect of gonadotrophin-releasing hormone agonist (GnRHa) treatment on intrauterine microbial colonization (IUMC) and the occurrence of endometritis was investigated. MAIN FINDINGS RESULTS: Lipopolysaccharide regulates the pro-inflammatory response in the pelvis and growth of endometriosis via the LPS/TLR4 cascade. The menstrual blood was highly contaminated with Escherichea coli and the endometrial samples were colonized with other microbes. A cross-talk between inflammation and ovarian steroids or the stress reaction also was observed in the pelvis. Treatment with GnRHa further worsens intrauterine microbial colonization, with the consequent occurrence of endometritis in women with endometriosis. CONCLUSION: For the first time, a new concept called the "bacterial contamination hypothesis" is proposed in endometriosis. This study's findings of IUMC in women with endometriosis could hold new therapeutic potential in addition to the conventional estrogen-suppressing agent.

Dp71 is regulated by phosphorylation and ubiquitin-proteasome system in neuronal cells.

The Dystrophin (Dp) gene is responsible for Duchenne muscular dystrophy (DMD), which is characterized by progressive muscular degeneration and variable degrees of cognitive impairment. Although Dp71 is the most abundant among the Dp isoforms in the brain, the regulatory mechanisms of the related expression levels have not been elucidated. In this study, we found that the constitutive expression levels of Dp71 in PC12 cells were sensitive to proteasomal inhibition. The ectopic expression of FLAG-tagged ubiquitin revealed that Dp71 was ubiquitinated intracellularly. Interestingly, proteasomal inhibition was accompanied by a posttranslational accumulation of modified Dp71, which was restored by protein phosphatase treatment in vitro, indicating that phosphorylation is responsible for the modification and affects the proteasome-dependent degradation of Dp71. Proteasomal activity-sensitive phosphorylated Dp71 is closely associated with syntrophin, a well-known binding partner of Dp71, and syntrophin is also regulated by proteasomal activity in a similar way to Dp71, suggesting that the posttranslational regulatory machinery for Dp71 level is coupled with Dp71-syntrophin molecular complex. Taken together, our results indicated that the expression levels of Dp71 are posttranslationally regulated by the phosphorylation-ubiquitin-proteasomal pathway, which may indicate the presence of regulatory mechanisms underlying the proteostasis of both Dp and its molecular complex, which may lead to better therapeutic approaches for the treatment of Dp-related diseases.

The role of L1cam in murine corticogenesis, and the pathogenesis of hydrocephalus.

L1cam (L1), one of the cell adhesion molecules belonging to the immunoglobulin superfamily, plays critical roles in neuronal migration, axon growth, guidance, fasciculation, and synaptic plasticity in the central as well as the peripheral nervous system. A number of X-linked forms of mental retardation have been associated with mutations in the L1 gene, including X-linked hydrocephalus in humans. Although model mice with different sites of L1 mutation have been studied, the pathogenetic mechanisms of hydrocephalus and mental retardation still remain unsolved. We herein present an overview of the function of L1 in the central nervous system and describe a human case of L1 mutation and knock-in mice that showed deleted sixth immunoglobulin of L1. Finally, we present experimental evidence showing that L1 is involved in murine neocortical histogenesis and propose a hypothetical mechanism of L1-linked hydrocephalus, with reference to corticogenesis.

An autopsy case of Balamuthia mandrillaris amoebic encephalitis, a rare emerging infectious disease, with a brief review of the cases reported in Japan.

Balamuthia mandrillaris is an amoeba found in fresh water and soil that causes granulomatous amoebic encephalitis. We report herein an autopsy case of B. mandrillaris amoebic encephalitis, which was definitely diagnosed by PCR. An 81-year-old man, who had Sjögren's syndrome, manifested drowsiness 2 months before his death with progressive deterioration. Neuroimaging demonstrated foci of T2- and fluid-attenuated inversion recovery high and T1 low-intensity with irregular post-contrast ring enhancement in the cerebral hemisphere, thalamus and midbrain. Pathologically, multiple hemorrhagic and necrotic lesions were found in the cerebrum, thalamus, midbrain, pons, medulla and cerebellum, which were characterized by liquefactive necrosis, marked edema, hemorrhage and necrotizing vasculitis associated with the perivascular accumulation of amoebic trophozoites, a few cysts, and the infiltration of numerous neutrophils and microglia/macrophages. The trophozoites were ovoid or round, 10-60 µm in diameter, and they showed foamy cytoplasm and a round nucleus with small karyosome in the center. The PCR and immunohistochemistry from paraffin-embedded brain specimens revealed angioinvasive encephalitis due to B. mandrillaris. Human cases of B. mandrillaris brain infection are rare in Japan, with only a few brief reports in the literature.

Adipose-derived stem cells promote proliferation, migration, and tube formation of lymphatic endothelial cells in vitro by secreting lymphangiogenic factors.

Adipose-derived stem cells (ADSCs) are a promising new therapeutic modality for several diseases and have been applied to various clinical fields because of their multidifferentiation potential and capacity for growth-factor secretion. Recently, 2 in vivo studies showed ADSCs to have potential applications in lymphedema therapy. However, it remains unclear whether ADSCs have direct effects on lymphatic endothelial cells (LECs). In this study, human LECs were treated with murine ADSC-derived conditioned media. Changes in LEC proliferation, migration, and tube formation were assessed by WST-8 assay, transwell chamber assay, and Matrigel-based tube formation assay, respectively, with recombinant human vascular endothelial growth factor-C used as a positive control. Additionally, the expression of several lymphangiogenic factors in ADSCs was examined by quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. Factors secreted by ADSCs induced LEC proliferation, migration, and tube formation more potently than recombinant human vascular endothelial growth factor-C. We confirmed by quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay that some of the lymphangiogenic factors of ADSCs were dramatically up-regulated under serum-starved conditions. These data indicate that ADSCs could directly contribute to lymphangiogenesis via secretory factors in vitro and may thus provide a therapeutic modality for patients with lymphedema.

Somatodendritic and excitatory postsynaptic distribution of neuron-type dystrophin isoform, Dp40, in hippocampal neurons.

The Duchenne muscular dystrophy (DMD) gene produces multiple dystrophin (Dp) products due to the presence of several promoters. We previously reported the existence of a novel short isoform of Dp, Dp40, in adult mouse brain. However, the exact biochemical expression profile and cytological distribution of the Dp40 protein remain unknown. In this study, we generated a polyclonal antibody against the NH2-terminal region of the Dp40 and identified the expression profile of Dp40 in the mouse brain. Through an analysis using embryonic and postnatal mouse cerebrums, we found that Dp40 emerged from the early neonatal stages until adulthood, whereas Dp71, an another Dp short isoform, was highly detected in both prenatal and postnatal cerebrums. Intriguingly, relative expressions of Dp40 and Dp71 were prominent in cultured dissociated neurons and non-neuronal cells derived from mouse hippocampus, respectively. Furthermore, the immunocytological distribution of Dp40 was analyzed in dissociated cultured neurons, revealing that Dp40 is detected in the soma and its dendrites, but not in the axon. It is worthy to note that Dp40 is localized along the subplasmalemmal region of the dendritic shafts, as well as at excitatory postsynaptic sites. Thus, Dp40 was identified as a neuron-type Dp possibly involving dendritic and synaptic functions.

Bisphenol A exposure disrupts the development of the locus coeruleus-noradrenergic system in mice.

It has been reported that bisphenol A (BPA), a widespread xenoestrogen employed in the production of polycarbonate plastics, affects brain development in both humans and rodents. In the present study employing mice, we examined the effects of exposure to BPA (500 µg/kg/day) during fetal and lactational periods on the development of the locus coeruleus (LC) at the age of embryonic day 18 (E18), postnatal 3 weeks (P3W), P8W and P16W. The number of tyrosine hydroxylase-immunoreactive cells (TH-IR cells) in females exposed to BPA was decreased, compared with the control females at P3W. At P8W, the number of TH-IR cells in females exposed to BPA was significantly decreased, compared with the control females, whereas the number of TH-IR cells in males exposed to BPA was significantly increased, compared with the control males, which resulted in reversed transient sexual differences in the numbers of TH-IR cells observed in the controls at P8W. However, no significant changes were demonstrated at E18 or P16W. Next, we examined the density of the fibers containing norepinephrine transporter (NET) in the anterior cingulate cortex (ACC) and prefrontal cortex, at P3W, P8W and P16W, because NET would be beneficial in identifying the targets of the LC noradrenergic neurons. There were no significant differences shown in the density of the NET-positive fibers, between the control and the groups exposed to BPA. These results suggested that BPA might disrupt the development of physiological sexual differences in the LC-noradrenergic system in mice, although further studies are necessary to clarify the underlying mechanisms.

Concomitant alpha-synuclein pathology in an autopsy case of amyotrophic lateral sclerosis presenting with orthostatic hypotension and cardiac arrests.

A 74-year-old man gradually developed muscular weakness in the upper extremities, followed by dyspnea and dysarthria over a 6-month period. He was admitted to our facility and diagnosed as having amyotrophic lateral sclerosis (ALS) based on clinical and neurophysiological findings. Two months later, transtracheal positive pressure ventilation (TPPV) was started. During his clinical course, orthostatic hypotension occurred a few times. He also had two episodes of transient cardiac arrest, and he died 15 months after disease onset. At autopsy, the brain, weighing 850 g, showed diffuse cortical atrophy, preferentially involving the frontal lobes. Microscopic findings included severe loss of neurons in the motor cortex, the motor nuclei of the brainstem and the anterior horns of the spinal cord, and mild loss of axons and myelin in the corticospinal tract. Trans-activation response DNA protein 43 (TDP-43) immunoreactive cytoplasmic inclusions, the pathognomonic findings for ALS, were noted in the nucleus facialis, nucleus ambiguus, and in the anterior horn of the spinal cord. In addition, Lewy bodies and Lewy neurites were found in the brainstem and in the nucleus intermediolateralis of the thoracic cord. The concomitant alpha-synuclein pathology may have been partly related to possible autonomic dysfunction underlying the two episodes of cardiac arrest.

Definite familial multiple system atrophy with unknown genetics.

Multiple system atrophy (MSA) is an oligodendrogliopathy of presumably sporadic origin, characterized by prominent α-synuclein inclusions with neuronal multisystem degeneration, although a few Mendelian pedigrees have been reported. Here we report two familial cases of MSA of unknown genetic background. One patient was diagnosed as a possible MSA-C (cerebellar dysfuntion) case, and the other as clinically possible MSA-P (parkinsonism), which turned out to be definite MSA, based on a detailed autopsy. The neuropathology showed extensive deposition of α-synuclein in the glia as well as in the neurons located in the cerebral cortices and hippocampal systems, although neither multiplication of the SNCA gene or mutations in COQ2 gene were identified in the family concerned.

Downregulation of L1 perturbs neuronal migration and alters the expression of transcription factors in murine neocortex.

L1 is a cell adhesion molecule associated with a spectrum of human neurological diseases, the most well-known being X-linked hydrocephalus. L1 knockout (L1-KO) mice have revealed a variety of functions of L1 that were crucial in brain development in different brain regions. However; the function of L1 in neuronal migration during cortical histogenesis remains to be clarified. We therefore investigated the corticogenesis of mouse embryos in which L1 molecules were knocked down in selected neurons, by employing in utero electroporation with shRNAs targeting L1 (L1 shRNA). Although more than 50% of the cells transfected with no small hairpin RNA (shRNA; monster green fluorescent protein: MGFP only) vector at embryonic day 13 (E13) reached the cortical plate at E16, significantly fewer (27%) cells transfected with L1 shRNA migrated to the same extent. At E17, 22% of cells transfected with the MGFP-only vector were found in the intermediate zone, and significantly more (34%) cells transfected with L1 shRNA remained in the same zone. Furthermore, the directions of the leading process of neurons transfected with L1 shRNA became more dispersed compared with cells with the MGFP-only vector. In addition, two transcription factors expressed in the neurons, Satb2 and Tbr1, were shown to be reduced or aberrantly expressed in neurons transfected with L1 shRNA. These observations suggest that L1 plays an important role in regulating the locomotion and orientation of migrating neurons and the expression of transcription factors during neocortical development that might partially be responsible for the abnormal tract formation seen in L1-KO mice.

Brain malformation with loss of normal FGFR3 expression in thanatophoric dysplasia type I.

Thanatophoric dysplasia is a lethal form of chondrodysplastic dwarfism in which the cerebral cortex displays a unique and complex malformation. We report a female case of thanatophoric dysplasia type I (TD1) with FGFR3 mutation. In this case, fetal ultrasonography at the 18th week of gestation led to a prenatal diagnosis of TD1 with characteristic bone features. The subject was stillborn at the 21st week of gestation, showing marked shortening of the long bones, small thorax and curved short femurs, but without a cloverleaf skull. The temporal lobe was enlarged and hyperconvoluted, appearing as broad gyri and deep sulci, which were composed of focal polymicrogyria-like shallow sulci and heterotopic neuroblastic nests in the intermediate zone and marginal zone. Abundant precursor cells, immunoreactive for nestin and Ki-67 were observed with scattered mitoses in the thickened inner intermediate and subventricular zones of the temporal and occipital lobes. The cytoarchitecture from the entorhinal cortex to Ammon's horn was disorganized with leptomeningeal glioneuronal heterotopia, immunoreactive for doublecortin and nestin. The expression of FGFR3 was virtually not discernible in the temporal and occipital lobes or in the hippocampus. Genetic analysis revealed a point mutation at C8526T (R248C) in the exon 7 of FGFR3. This is the first report that demonstrates that overproduction of intermediate progenitor cells might be induced by FGFR3 mutation in a human TD1 case.

LIS1 and NDEL1 coordinate the plus-end-directed transport of cytoplasmic dynein.

LIS1 was first identified as a gene mutated in human classical lissencephaly sequence. LIS1 is required for dynein activity, but the underlying mechanism is poorly understood. Here, we demonstrate that LIS1 suppresses the motility of cytoplasmic dynein on microtubules (MTs), whereas NDEL1 releases the blocking effect of LIS1 on cytoplasmic dynein. We demonstrate that LIS1, cytoplasmic dynein and MT fragments co-migrate anterogradely. When LIS1 function was suppressed by a blocking antibody, anterograde movement of cytoplasmic dynein was severely impaired. Immunoprecipitation assay indicated that cytoplasmic dynein forms a complex with LIS1, tubulins and kinesin-1. In contrast, immunoabsorption of LIS1 resulted in disappearance of co-precipitated tubulins and kinesin. Thus, we propose a novel model of the regulation of cytoplasmic dynein by LIS1, in which LIS1 mediates anterograde transport of cytoplasmic dynein to the plus end of cytoskeletal MTs as a dynein-LIS1 complex on transportable MTs, which is a possibility supported by our data.

Bisphenol A, an endocrine-disrupting chemical, and brain development.

Bisphenol A (BPA) is an endocrine-disrupting chemical, widely used in various industries and the field of dentistry. The consequent increase in BPA exposure among humans has led us to some concerns regarding the potential deleterious effects on reproduction and brain development. The emphasis of this review is on the effects of prenatal and lactational exposure to low doses of BPA on brain development in mice. We demonstrated that prenatal exposure to BPA affected fetal murine neocortical development by accelerating neuronal differentiation/migration during the early embryonic stage, which was associated with up- and down-regulation of the genes critical for brain development, including the basic helix-loop-helix transcription factors. In the adult mice brains, both abnormal neocortical architecture and abnormal corticothalamic projections persisted in the group exposed to the BPA. Functionally, BPA exposure disturbed murine behavior, accompanied with a disrupted neurotransmitter system, including monoamines, in the postnatal development period and in adult mice. We also demonstrated that epigenetic alterations in promoter-associated CpG islands might underlie some of the effects on brain development after exposure to BPA.

Loss of adenomatous polyposis coli in Bergmann glia disrupts their unique architecture and leads to cell nonautonomous neurodegeneration of cerebellar Purkinje neurons.

The tumor suppressor adenomatous polyposis coli (APC) is a multifunctional protein that inhibits the Wnt/beta-catenin signaling pathway and regulates the microtubule and actin cytoskeletons. Using conditional knockout (CKO) mice in which the APC gene is inactivated in glial fibrillary acidic protein (GFAP)-expressing cells, we show a selective and critical role for APC in maintaining the morphology and function of cerebellar Bergmann glia, which are specialized astroglia that extend polarized radial processes from the Purkinje cell layer to the pial surface. APC-CKO mice developed Bergmann glia normally until the accumulation of beta-catenin started around postnatal day 10 (P10). Their radial fibers then became shortened with a marked reduction of branching collaterals and their cell bodies translocated into the molecular layer followed by loss of their pial contact and transformation into stellate-shaped cells by P21. Purkinje neurons were normal in appearance and number at P21, but there was significant loss of Purkinje neurons and cerebellar atrophy by middle age. Outside the cerebellum, neither beta-catenin accumulation nor morphological changes were identified in GFAP-expressing astroglia, indicating region-specific effects of APC deletion and an essential role for APC in maintaining the unique morphology of Bergmann glia as compared with other astroglia. These results demonstrate that loss of APC selectively disrupts the Bergmann glial scaffold in late postnatal development and leads to cerebellar degeneration with loss of Purkinje neurons in adults, providing another potential mechanism for region-specific non-cell autonomous neurodegeneration.

Adenomatous polyposis coli is essential for both neuronal differentiation and maintenance of adult neural stem cells in subventricular zone and hippocampus.

The tumor suppressor adenomatous polyposis coli (APC) is a multifunctional protein that not only inhibits the Wnt signaling pathway by promoting the degradation of ß-catenin but also controls cell polarity, motility, and division. APC is abundantly expressed in the adult central nervous system, but its role in adult neurogenesis remains unknown. Using conditional deletion (or knockout) of APC (APC-CKO) from glial fibrillary acidic protein (GFAP)-expressing cells including adult neural stem cells (NSCs) in the subventricular zone and hippocampal dentate gyrus, we show that APC expression by these cells is a critical component of adult neurogenesis. Loss of APC function resulted in a marked reduction of GFAP-expressing NSC-derived new neurons, leading to the decreased volume of olfactory granule cell layer. Two distinct mechanisms account for impaired neurogenesis in APC-CKO mice. First, APC was highly expressed in migrating neuroblasts and APC deletion disturbed the differentiation from Mash1-expressing transient amplifying cells to neuroblasts with concomitant accumulation of ß-catenin. As a result, migrating neuroblasts decreased, whereas Mash1-expressing dividing cells reciprocally increased in the olfactory bulb of APC-CKO mice. Second, APC deletion promoted an exhaustion of the adult germinal zone. Functional NSCs and their progeny progressively depleted with age. These findings demonstrate that APC expression plays a key role in regulating intracellular ß-catenin level and neuronal differentiation of newly generated cells, as well as maintaining NSCs in the adult neurogenic niche. STEM CELLS 2010;28:2053-2064.

Prenatal and Lactational Exposure to Bisphenol A in Mice Alters Expression of Genes Involved in Cortical Barrel Development without Morphological Changes.

It has been reported that premature infants in neonatal intensive care units are exposed to a high rate of bisphenol A (BPA), an endocrine disrupting chemical. Our previous studies demonstrated that corticothalamic projection was disrupted by prenatal exposure to BPA, which persisted even in adult mice. We therefore analyzed whether prenatal and lactational exposure to low doses of BPA affected the formation of the cortical barrel, the barreloid of the thalamus, and the barrelette of the brainstem in terms of the histology and the expression of genes involved in the barrel development. Pregnant mice were injected subcutaneously with 20 µg/kg of BPA daily from embryonic day 0 (E0) to postnatal 3 weeks (P3W), while the control mice received a vehicle alone. The barrel, barreloid and barrelette of the adult mice were examined by cytochrome C oxidase (COX) staining. There were no significant differences in the total and septal areas and the patterning of the posterior medial barrel subfield (PMBSF), barreloid and barrelette, between the BPA-exposure and control groups in the adult mice. The developmental study at postnatal day 1 (PD1), PD4 and PD8 revealed that the cortical barrel vaguely appeared at PD4 and completely formed at PD8 in both groups. The expression pattern of some genes was spatiotemporally altered depending on the sex and the treatment. These results suggest that the trigeminal projection and the thalamic relay to the cortical barrel were spared after prenatal and lactational exposure to low doses of BPA, although prenatal exposure to BPA was previously shown to disrupt the corticothalamic projection.